The present invention relates to the technical field of tires, in particular tires of civil engineering vehicles and the like (in the sector of intensive agriculture, vehicles operating in ports, and the like), and more generally at all sites where such heavy vehicles operates in conditions which are stable or at least stable for a sufficient period (for example, on a single site there may be a period of stable conditions in a “dry season” and other stable conditions in a “rainy season”, and the like); to be more precise, the invention relates to a method for evaluating the difference between the situation of a site at a given moment and a reference or normal state as regards the operating conditions of such tires over a period of time corresponding to stable operating conditions.
Tires for construction and other, similar vehicles represent a considerable cost for the operating companies of sites such as surface mines, civil engineering and similar operations. The cost of tires may come to up to 20% of the operating costs. The rough cost of large tires of this kind is in the order, depending on the item of plant and its size, of 8000 (for a 33.00R51; 38-tonne load-carrying capacity for each tire) to 25000 (for a 59/80 R 63, with 100-tonne capacity) for each tire.
For a surface mine, which is the example application most representative of the applications of the invention, depending on the size the cost of tires may be 5 to 10 million or even 15 million per year, based on vehicles equipped with six tires and complete replacement of the vehicle tires after one year.
It will readily be appreciated, therefore, that operating companies take considerable note of the service life of these tires.
It will also readily be appreciated that if the tires do not last as long as the anticipated service life, there is an urgent need for the operating company, given its profitability targets, to remedy the problem. This is all the more true since, in addition to the cost of the tires, the profitability calculations for the site are affected by the fact that heavy vehicles are rendered immobile when they should not be.
Moreover, the tire manufacturer's interests tend in the same direction, that is to seek to understand the cause of premature tire degradation so that its manufacturing is not implicated.
Despite the vast economic stakes for both the operating company of a site and the manufacturer, there has not hitherto been any method allowing the causes of premature tire degradation to be understood and analyzed. People make do with empirical examinations and replacing tires (of which we have already seen the cost), both measures which do not allow any solution to be found.
There is thus a major need, even though this does not seem to have been recognized in the prior art, or has been considered impossible to meet at reasonable cost, for a process allowing abnormal degradation in a tire of a civil engineering vehicle or the like to be attributed to objective causes relating to the characteristics of the site at which the vehicles operate.